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Structural insights into the function of ZRANB3 in replication stress response
Marek Sebesta1, Christopher D O Cooper1, Antonio Ariza1
1Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
Nature Communications
|June 17, 2017
Summary
The study reveals how ZRANB3, an enzyme crucial for genome stability, is regulated at stalled DNA replication forks by PCNA. This provides insights into cancer-associated mutations.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Replication blocks threaten genome stability, necessitating robust cellular stress responses.
- ZRANB3, an ATP-dependent endonuclease, plays a role in resolving replication stress.
- Understanding ZRANB3 regulation is key to comprehending DNA replication fidelity.
Purpose of the Study:
- To elucidate the structural and functional mechanisms regulating ZRANB3 activity.
- To define the role of PCNA in recruiting and activating ZRANB3 at stalled replication forks.
- To interpret the functional implications of cancer-associated ZRANB3 mutations.
Main Methods:
- X-ray crystallography to determine the structure of the ZRANB3 HNH endonuclease domain.
- Biochemical assays to analyze ZRANB3 activity.
- Co-crystallization of PCNA with ZRANB3 motifs (PIP box and APIM) to reveal interaction structures.
Main Results:
- The structure of the ZRANB3 HNH domain was determined.
- PCNA was identified as a key regulator that recruits and stimulates ZRANB3 at stalled forks.
- Co-crystal structures revealed the interaction between PCNA and ZRANB3 motifs, highlighting similarities between PIP and APIM motifs.
- A multi-layered regulatory mechanism involving PCNA and ATP-dependency for ZRANB3 activity at replication forks was proposed.
Conclusions:
- PCNA acts as a crucial scaffold, recruiting and activating ZRANB3 at stalled replication forks.
- The structural insights into PCNA-ZRANB3 interactions explain the enzyme's regulation and the impact of cancer mutations.
- ZRANB3's activity is finely tuned by PCNA and ATP-dependency, ensuring genome stability during replication stress.
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